Bombardier Inc. secured a surprise victory Friday that will reopen the largest aerospace market in the world to its marquee CSeries jet after a top U.S. trade body rejected the nearly 300 per cent duties imposed against the planemaker in December.

In a stunning 4-0 decision, the U.S. International Trade Commission ruled that Bombardier rival the Boeing Co. was not materially injured or threatened by the sale of 75 CSeries jets to Delta Air Lines Ltd. and as a result reversed massive duties issued against Bombardier by the U.S. Department of Commerce.

The vote marks the final step in an investigation that Boeing launched nine months ago, arguing that Bombardier had dumped its marquee jet into the U.S. market and offered it to Delta Air Lines Ltd. “at absurdly low prices.”

The unanimous decision came as a surprise to aviation analysts, who had overwhelmingly anticipated a ruling in Boeing’s favour. Bombardier’s stock surged 19 per cent to $3.67 moments after the decision was made public, before paring some gains to close at $3.54.

On Monday the stock was trading up 17 per cent at $3.68.

The ruling also means that Bombardier can move ahead with the delivery of its CSeries jets to Delta, originally scheduled to begin in the spring.

“Today’s decision is a victory for innovation, competition and rule of law,” Bombardier said in a statement released shortly after the vote.

“The CSeries is the most innovative and efficient new aircraft in a generation. Its development and production represent thousands of jobs in the United States, Canada, and the United Kingdom…. With this matter behind us, we are moving full speed ahead with finalizing our partnership with Airbus.”

Boeing said in a statement it is disappointed with the decision and that the commission “did not recognize the harm that Boeing has suffered from the billions of dollars in illegal government subsidies that the Department of Commerce found Bombardier received and used to dump aircraft in the U.S. small single-aisle airplane market.”

The U.S.-based aerospace company said it will review the commission’s detailed opinions when they are released at a later date.

“Boeing remains confident in the facts of our case and will continue to document any harm to Boeing and our extensive U.S. supply chains that results from illegal subsidies and dumped pricing,” the company said in a statement.

Boeing can still appeal the decision through the U.S. Court of International Trade or launch a challenge with the World Trade Organization, although trade lawyer Mark Warner said an appeal would be “unlikely to succeed.”

The ruling is a significant win for not only Bombardier, but the Canadian, Quebec and U.K. governments, which defended Bombardier and its CSeries program throughout the trade dispute.

Canada’s foreign minister Chrystia Freeland commended the ITC decision, saying in a statement that “it will support well-paying middle-class jobs on both sides of the border.” U.K. Prime Minister Theresa May said on Twitter that she welcomed the decision, “which is good news for British industry.”

Boeing remains confident in the facts of our case and will continue to document any harm to Boeing and our extensive U.S. supply chains that results from illegal subsidies and dumped pricing

Boeing statement

Bombardier had argued that the commission should reject the petition in part due to its new blockbuster partnership with Airbus SE, which will see the European planemaker take control of the CSeries program and assemble U.S.-bound jets in a facility in Alabama.

Within an hour of the decision, Bombardier chief executive Alain Bellemare and his Airbus counterpart Tom Enders were toasting glasses of champagne in the offices in Montreal.

“Integration planning is going well and we look forward to delivering the CSeries to the U.S. market so that the U.S. airlines and the U.S. flying public can enjoy the many benefits of this remarkable aircraft,” Bombardier said in a statement.

Richard Aboulafia, an aviation analyst and vice-president of Teal Group, said while the ITC decision removes uncertainties moving forward in the U.S. market, the dynamics behind the deal that drove Bombardier into the arms of Airbus remain.

“The CSeries might be a very good jet, but niche players don’t stand much of a chance competing in the large jetliner business,” he said.

“You still had a lot of customers out there who didn’t want to run the risk of buying an orphaned product … It never had the kind of product support arrangements, (or) the kind of competitive buyer pricing arrangements that Airbus could provide.”

Macquarie Research analyst Konark Gupta said the delivery of jets to Delta this year would remove remaining uncertainty around CSeries production ramp-up, and potentially lead to more order wins in the U.S. Delta said in a statement that it was pleased with the decision and that “the airline looks forward to introducing the innovative CS100 to its fleet for the benefit of Delta’s employees, customers and shareowners.”

“It is quite possible that those order discussions could get alive following the U.S. ITC ruling and potentially translate into CSeries orders,” Gupta wrote in a note to clients Friday. “We believe most of the U.S. airlines would be considering CSeries jets now that the U.S. tariff uncertainty is over.”